Glacier Variation In Tergun Daba Qilian Mountains In The Past 30 Years

Global warming has become an indisputable fact.It can involve the entire state of human survival,studies on the global warming gradually become a hot spot.Glaciers,as indicators of climate change,are most sensitive to climate change.Glacial retreat or accumulation are the two response form of glaciers to climate change.Many studies indicated that glacier retreat after the Little Ice Age,and this trend is more obvious after the stage of industrialization.Qinghai Tibet Plateau,as one of the three poles of the earth,is closest to human living environment.The glacial retreat in this area is more serious than other areas.However,because the area of the Qinghai Xizang Plateau is about 2.5×10⁶ km²,the range of the glaciers is varied,the physical properties of the glaciers,the types of glaciers and the spatial distribution of different types of glaciers are different,so the response to environmental changes is different.In view of this situation,using the Landsat remote sensing satellite image data of 1987,1997,2007 and 2016,by using remote sensing interpretation,we extract the distribution of glaciers in Tergun Daba of the four periods,and analyze the temporal and spatial distribution and variation of the past 30 years.Combined with topography and other environmental factors,the spatial and temporal evolution and structure of glaciers are qualitatively described and combined with quantitative statistics.Firstly,the background and significance of glacier change research are clarified,and the related research at home and abroad is reviewed and summarized,the research content and technical scheme are determined.Secondly,we describe the natural climatic factors related to Glacier development,such as hydrology,vegetation and meteorology.The distribution of glaciers in four periods in recent 30 years was extracted by remote sensing classification.Combined with terrain factors,the spatial distribution and variation of inner glaciers were statistically analyzed,the relationship with environmental factors and glacier variation was studied.The evolution of glaciers in the next 15 and 30 years is simulated based on brightness temperature change.Finally,comparing the changes of glacier in Tergun Daba and other areas.The results show that the retreat of the glacier in Tergun Daba is serious,the area of the glacier is reduced from 808.8 km² in 1987 to 429.4 km² in 2016.The total retreat rate in 30 years is 46.9%and the annual percentages of area changes is1.6%·a^-1.The terrain distribution of glacier has its regular pattern:5000-5200 m,10-15 degree slope,North and northeast direction,and glacier is most developed.Glacial retreat also has terrain characteristics:the middle and lower parts of the mountain,the most significant change in the South and Southeast direction.The results support the conclusion that the glaciers are generally shrinking in recent decades,but in some time,the glacier area has increased slightly.The trend of the glacier variation was opposite to that of the variation of glacial lakes.Glacier variation can improve the vegetation.Temperature change plays a dominant role on glacier variation.The simulation of future glaciers shows that the retreating rate of glacier will keep high rate in the next thirty years.